Magnetic disk device

ABSTRACT

A magnetic disk device includes a magnetic disk for recording information, a spindle motor for driving the magnetic disk for rotation, a magnetic head for writing information to and reading information from the magnetic disk, a carriage arm supporting the magnetic head, a voice coil motor for moving the carriage arm, a shroud forming a peripheral wall, an air passage passing between the voice coil motor and the shroud and connecting an upper side of the carriage arm with respect to the direction of rotation of the magnetic disk to a lower side of the carriage arm, and a filter. The filter is placed away from an outer edge of the magnetic disk and wholly within the air passage to clean air inside the disk drive.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of U.S. application Ser. No.09/986,605, filed Nov. 9, 2001, which is a continuation of U.S.application Ser. No. 09/769,362, filed Jan. 26, 2001, (now U.S. Pat. No.6,369,977).

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a magnetic disk device and, moreparticularly, to a magnetic disk drive which has a high reliability andis capable of reducing windage vibrations of a magnetic head due toturbulent air currents produced by a rotating magnetic disk.

[0003]FIG. 6 shows a known magnetic disk device 600 disclosed in JP-ANo. 2000-156068. The magnetic disk device 600 drives a magnetic disk 11by way of a spindle motor 12. A magnetic head for writing information toand reading information from the magnetic disk 11 is supported on theextremity of a suspension 21. A carriage arm 25 supports the suspension21. The carriage arm 25 has a base end fixed to a pivot shaft 20. Avoice coil motor 28 drives the carriage arm 25 for turning. This priorart magnetic disk device 600 is provided with a filter 60 placed on anair passage 61 formed by cutting a portion of a shroud 41.

SUMMARY OF THE INVENTION

[0004] The air passage 61 formed by cutting a portion of the shroud 41as shown in FIG. 6 often enhances the hydrodynamic vibrations of themagnetic disk 11 generally called disk fluttering

[0005] Accordingly, it is an object of the present invention to providea magnetic disk device which has a high reliability and is capable ofreducing windage vibrations of a magnetic head caused by air currentsproduced by a rotating magnetic disk.

[0006] With the foregoing object in view, according to a first aspect ofthe present invention, a magnetic disk device comprises a magnetic diskfor recording information, a spindle motor for driving the magnetic diskfor rotation, a magnetic head for writing information to and readinginformation from the magnetic disk, a carriage arm supporting themagnetic head, a voice coil motor for moving the carriage arm, a shroudforming a peripheral wall, a structure forming an air passage extendingthrough a clearance between the voice coil motor and the shroud betweena position on the upper side of the carriage arm with respect to thedirection of rotation of the magnetic disk and a position on the lowerside of the carriage arm with respect to the direction of rotation ofthe magnetic disk, and a filter placed in the air passage to clean airflowing through the air passage.

[0007] According to a second aspect of the present invention, a magneticdisk device comprises a magnetic disk for recording information, aspindle motor for driving the magnetic disk for rotation, a magnetichead for writing information to and reading information from themagnetic disk, a carriage arm supporting the magnetic head, a voice coilmotor for moving the carriage arm, a loading/unloading mechanism forretracting the carriage arm from a position on the magnetic disk, ashroud forming a peripheral wall, and a structure forming an air passageextending through a clearance between the voice coil motor and theshroud between a position on the upper side of the carriage arm withrespect to the direction of rotation of the magnetic disk and a positionon the lower side of the carriage arm with respect to the direction ofrotation of the magnetic disk.

[0008] According to a third aspect of the present invention, a magneticdisk device comprises a magnetic disk for recording information, aspindle motor for driving the magnetic disk for rotation, a magnetichead for writing information to and reading information from themagnetic disk, a carriage arm supporting the magnetic head, a voice coilmotor for moving the carriage arm, a loading/unloading mechanism forretracting the carriage arm from a position on the magnetic disk, and ashroud forming a peripheral wall; wherein the rotating direction of themagnetic disk is the same as a direction from the free end of thecarriage arm toward the base end of the same.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The invention disclosed herein will be understood better withreference to the following drawings of which:

[0010]FIG. 1 is a schematic plan view of a magnetic disk devicerepresenting a first embodiment according to the present invention;

[0011]FIG. 2 is a schematic plan view of a magnetic disk devicerepresenting a second embodiment according to the present invention;

[0012]FIG. 3 is a schematic plan view of a magnetic disk devicerepresenting a third embodiment according to the present invention;

[0013]FIG. 4 is a schematic plan view of a magnetic disk devicerepresenting a fourth embodiment according to the present invention;

[0014]FIG. 5 is a graph showing the results of experiments on pressurevariation; and

[0015]FIG. 6 is a plan view of a prior art magnetic disk device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Preferred embodiments of the present invention will be describedby way of example with reference to the accompanying drawings.

[0017] First Embodiment

[0018] Referring to FIG. 1, which shows a magnetic disk device 100representing a first embodiment according to the present invention, amagnetic disk 11 is driven for rotation by a spindle motor 12. Amagnetic head for writing information to and reading information fromthe magnetic disk 11 is supported on the extremity of a suspension 21supported on a carriage arm 25. The carriage arm 25 is capable ofturning on a pivot shaft 26. A voice coil motor 28 drives the carriagearm 25 for turning. The rotating direction of the magnetic disk 11 isthe same as a direction from the base end of the suspension 21 towardthe extremity of the same. A connector 10 connects input and outputsignal lines, not shown, extending from the magnetic head supported onthe suspension 21 to a control circuit, not shown, which is included inthe magnetic disk device 100. A loading/unloading mechanism 31 in theform of a lumped loading system is disposed so that a tab 32 slides ontothe loading/unloading mechanism 31 when the carriage arm 25 is turned toa position outside the magnetic disk 11.

[0019] A shroud 41 has a wall surrounding the magnetic disk 11. Theshroud 41 and a land 39 form return channels 45 a, 45 b and 45 c, i.e.,air passages, through which air currents produced when the magnetic disk11 is rotated flow. A filter 60 for removing dust is placed in thereturn channel 45 c. The return channel 45 c is connected to an airpassage 50 defined by an extension 42. Air currents produced when themagnetic disk 11 is rotated flow into the return channel 45 a, flowthrough the return channels 45 b and 45 c and the air passage 50, andflow outside through an exit 49 formed at a position below theloading/unloading mechanism 31 with respect to the direction of flow ofthe air currents. The air currents flow also through a space immediatelyabove the loading/unloading mechanism 31 into the air passage 50 andflow outside through the exit 49 b.

[0020] In the magnetic disk device 100, spaces on the upper and thelower side of the loading/unloading mechanism 31 are connected by theair passage 50, and a screen 42 b screens a principal section of the airpassage 50 from the magnetic disk 11 so that air flows smoothlydownstream to prevent the production of turbulent air currents aroundthe loading/unloading mechanism. Thus, enhancement of windage vibrationsof the magnetic head due to turbulent air currents can be prevented andthe reliability of the magnetic disk device can be enhanced.

[0021] The fluttering amplitude of the magnetic disk 11 on the magneticdisk device 100 provided with the filter 60 in the return channel 45 bor 45 c was smaller by about 27% than that of a magnetic disk on aconventional magnetic disk device provided with an air passage speciallyfor a filter.

[0022] The effect of placing the filter in the return channel inreducing the fluttering amplitude of the magnetic disk 11 is effectivenot only in magnetic disk devices provided with a loading/unloadingmechanism, but also in magnetic disk devices of a CSS (contact startstop) system in which a magnetic head is in sliding contact at the startand stop of rotation of the magnetic disk.

[0023] The filter 60 may be placed in the return channel 45 a or 45 b.Experiments proved that flutter reduction when the filter 60 is placedat the inlet of the return channel 45 a was greater by about 10% thanthose when the filter 60 was placed at other positions. The effect ofair on cooling the voice coil motor 28 can be enhanced by placing thefilter 60 in the return channel 45 b between the voice coil motor 28 andthe shroud 41.

[0024] Second Embodiment

[0025] A magnetic disk device 200 representing a second embodimentaccording to the present invention will be described with reference toFIG. 2, in which parts like or corresponding to those of the magneticdisk device 100 in the first embodiment will be denoted by the samereference numerals and a respect of the description thereof will beomitted.

[0026] The magnetic disk device 200 is provided with a screen 43 toproduce smooth air currents around a loading/unloading mechanism 31. Thescreen 43 covers a region on one side of the loading/unloading mechanism31 spaced from the magnetic disk 11, i.e., on the opposite side of themechanism 31 from the magnetic disk 11, and extends into a region on thelower side of the loading/unloading mechanism 31 with respect to therotating direction of the magnetic disk 11. A portion 44 of a shroud 41is shaped so that the width of the air passage 50 decreases gradually.

[0027] The air passage 50 is defined by a portion of the screen 43 onthe lower side of the loading/unloading mechanism 31 with respect to thedirection of air flow, and the shroud 41. Air flows through an entrance49 a into the air passage 50 and flows outside the air passage 50through an exit 49 b. The screen 43 is shaped so as to guide air so thatair flows smoothly and screens a principal section of the air passage 50from the magnetic disk 11. The exit 49 b is located on a line passingthrough the center of the magnetic disk 11 and at an angle θ about thecenter of the magnetic disk 11 measured in the rotating direction of themagnetic disk 11 from a line passing through the center of the magneticdisk 11 and the loading/unloading mechanism 31 (head stroke position).Preferably, the angle θ is in the range of 10° to 30°, more preferably,in the range of 15° to 25°. Turbulent flow of air is producedunavoidably in the vicinity of the exit 49 b, and, if the angle θ isbelow 10°, the exit 49 b will be excessively near to theloading/unloading mechanism 31 and turbulent flow of air produced at theexit 49 b will adversely affect the function of the loading/unloadingmechanism 31. Consequently, the turbulence control effect of themagnetic disk device will be unsatisfactory. When the angle θ is greaterthan 30°, the shroud 41 is excessively short and the exciting force thatcauses the magnetic disk 11 to flutter increases.

[0028] In the magnetic disk device 200 in the second embodiment, thescreen 43 covers the region on one side of the loading/unloadingmechanism 31 spaced from the magnetic disk 11 and extends into theregion on the lower side of the loading/unloading mechanism 31 withrespect to the rotating direction of the magnetic disk 11. Therefore,the production of turbulent flow of air by the irregular shape of theloading/unloading mechanism 31 can be prevented and air is able to flowsmoothly.

[0029] Since the air currents produced by the rotating magnetic disk 11flow in a direction opposite the rotating direction of the magnetic disk11 with respect to the loading/unloading mechanism 31, the collision ofthe air currents against the loading/unloading mechanism 31 and theresultant turbulent flow of air can be prevented. Thus, it is possibleto prevent the deterioration of the reliability of the magnetic diskdevice 200 caused by the enhancement of windage vibrations of themagnetic head by the loading/unloading mechanism 31, the enhancement ofexciting force that causes the magnetic disk 11 to flutter, and theunstable loading and unloading operations due to the adverse effect ofturbulent flow on the suspension 21 and the carriage arm 25.

[0030] Third Embodiment

[0031] A magnetic disk device 300 representing a third embodimentaccording to the present invention will be described with reference toFIG. 3, in which parts like or corresponding to those of the magneticdisk devices 100 and 200 in the first and the second embodiment will bedenoted by the same reference numerals, and a repeated descriptionthereof will be omitted.

[0032] The magnetic disk device 300 is basically the same inconstruction as the magnetic disk device 200 in the second embodiment.The magnetic disk device 300 is provided with a screen 43 a that extendsfrom the upper side to the lower side of a loading/unloading mechanism31 to guide air currents more smoothly from the upper side of theloading/unloading mechanism 31 into an air passage 50. A filter 60 isplaced in a passage between an extension 42 and the screen 43 a.

[0033] In the magnetic disk device 300 in the third embodiment, thestability of air currents flowing from the upper side toward the lowerside of the loading/unloading mechanism 31 can be enhanced because thescreen 43 a extends from the upper side to the lower side of theloading/unloading mechanism 31. Experiments show that the screen 43 aincreases flutter reducing effect by about 10%. The filter 60, similarlyto that of the first or the second embodiment, may be disposed in thereturn channel 45 a or 45 b.

[0034] Fourth Embodiment

[0035] A magnetic disk device 400 representing a fourth embodimentaccording to the present invention will be described with reference toFIG. 4, in which parts like or corresponding to those of the magneticdisk devices 100, 200 and 300 in the first, the second and the thirdembodiment will be denoted by the same reference numerals, and arepeated description thereof will be omitted.

[0036] This magnetic disk device 400 drives a magnetic disk 11 by way ofa spindle motor 12. The magnetic disk 11 is rotated in a directionopposite the direction in which the magnetic disks 11 in the first tothe third embodiments are rotated; that is, the magnetic disk 11 isrotated in a direction from a loading/unloading mechanism 31 toward asuspension 21, in a direction from the extremity toward the base end ofthe suspension 21 or in a direction from a magnetic head toward acarriage arm 25 supporting the suspension 21.

[0037] In a magnetic disk device of a CSS system, the magnetic diskcannot be turned in the reverse direction because troubles, such asbuckling, occur in the gimbals and the suspension of the magnetic diskdevice when the magnetic disk is rotated in the reverse direction. Themagnetic disk device provided with the loading/unloading mechanism 31 isfree from such troubles even if the magnetic disk is rotated in thereverse direction.

[0038] A shroud 41 and a land 39 define return channels 45 a, 45 b and45 c through which air currents produced by a rotating magnetic disk 11flow. A filter 60 is placed in the return channel 45 c to filter outdust from the air. An extension 42 connects the return channel 45 c toan air passage 50. The filter 60, similarly to that of the first or thesecond embodiment, may be placed in the return channel 45 a or 45 b.

[0039] The air passage 50 is defined by a screen 43 b disposed on theupper side of the loading/unloading mechanism 31. Air flows through anentrance 49 a on the upper side of the loading/unloading mechanism 31into the air passage 50 and flows out of the air passage 50 through anexit 49 b on the lower side of the loading/unloading mechanism 31. Thescreen 43 b is shaped so as to guide air so that air flows smoothly, andscreens a principal section of the air passage 50 from the magnetic disk11. The screen 43 b is extended on the upper side of theloading/unloading mechanism 31 with respect to the direction of airflow. Air currents produced by the rotating magnetic disk 11 flowthrough the entrance 49 a into the air passage 50, flow out of the airpassage 50 through the exit 49 b and flow through the return channels 45c, 45 b and 45 a.

[0040]FIG. 5 shows measured ranges of pressure variation at positions atangles 90 °, 180° and 270° in the rotating direction of the magneticdisk 11 from a reference line at an angular position of 0° correspondingto the position of the carriage arm 25. As obvious from FIG. 5, therange of pressure variation decreases with the angle from the referenceline. When the magnetic disk 11 is rotated in the direction indicated bythe arrow in FIG. 4, the range of pressure variation is the widest in aregion between the carriage arm 25 and the exit of the return channel 45a, extending under an open section of the shroud 41, i.e., a sectionbetween the entrance 49 a of the passage defined by the shroud 41 andthe magnetic disk 11 and a position where the passage defined by theland 39 and the magnetic disk 11 is narrowed. The range of pressurevariation is the narrowest in a region around the entrance 49 a on theupper side of the open section of the shroud 41.

[0041] Since the head 11 of the magnetic disk device 400 in the fourthembodiment is located at an angular position corresponding to the regionaround the entrance 49 a on the upper side of the open section of theshroud 41, where the range of pressure variation is the narrowest, thewindage vibrations of the head 11 can be prevented, thereby to enhancethe reliability of the magnetic disk device 400.

[0042] The mode of variation of the range of pressure variation in amagnetic disk device not provided with any return channels is the sameas that shown in FIG. 5. The effect of the magnetic disk device 400 inthe fourth embodiment can be attained also in a magnetic disk device notprovided with any return channels.

[0043] As apparent from the foregoing description, the magnetic diskdevice according to the present invention is capable of reducing windagevibrations of the head caused by air currents generated by the rotatingmagnetic disk, which enhances the reliability of the magnetic diskdevice.

[0044] Although the invention has been described in its preferredembodiments with a certain degree of particularity, obviously manychanges and variations are possible therein. It is therefore to beunderstood that the present invention may be practiced otherwise than asspecifically described herein without departing from the scope andspirit thereof.

What is claimed is:
 1. A magnetic disk device comprising: a magneticdisk for recording information; a spindle motor for driving the magneticdisk for rotation; a magnetic head for writing information to andreading information from the magnetic disk; a carriage arm supportingthe magnetic head; a voice coil motor for moving the carriage arm; ashroud forming a peripheral wall; an air passage passing between thevoice coil motor and the shroud, and connecting an upper side of thecarriage arm with respect to the direction of rotation of the magneticdisk to a lower side of the carriage arm; and a filter placed away froman outer edge of the magnetic disk and wholly within the air passage toclean air inside the disk drive.
 2. The magnetic disk drive according toclaim 1, wherein said filter is placed inside the air passage formed bythe voice coil motor and the shroud.
 3. The magnetic disk driveaccording to claim 1, wherein said filter is placed in a lower side ofthe air passage.
 4. The magnetic disk drive according to claim 1,wherein a direction of rotation of the magnetic disk is the same as thedirection from a portion of the carriage arm supporting the magnetichead toward a base end of the carriage arm.
 5. A magnetic disk devicecomprising: a magnetic disk for recording information; a spindle motorfor driving the magnetic disk for rotation; a magnetic head for writinginformation to and reading information from the magnetic disk; acarriage arm supporting the magnetic head; a voice coil motor for movingthe carriage arm; a loading/unloading mechanism for retracting thecarriage arm from a position on the magnetic disk; a shroud forming aperipheral wall; an air passage passing between the voice coil motor andthe shroud, and connecting an upper side of the carriage arm withrespect to the direction of rotation of the magnetic disk to a lowerside of the carriage arm; and a filter placed away from an outer edge ofthe magnetic disk and wholly within the air passage to clean air insidethe disk drive.
 6. The magnetic disk drive according to claim 5, whereinsaid filter is placed inside the air passage formed by the voice coilmotor and the shroud.
 7. The magnetic disk drive according to claim 5,wherein said filter is placed in a lower side of the air passage.
 8. Themagnetic disk drive according to claim 5, wherein a direction ofrotation of the magnetic disk is the same as the direction from aportion of the carriage arm supporting the magnetic head toward a baseend of the carriage arm.
 9. The magnetic disk drive according to claim5, further comprising a screen extending along the magnetic disk in aregion on an upper side of the loading/unloading mechanism with respectto the direction of rotation of the magnetic disk.
 10. The magnetic diskdrive according to claim 5, further comprising a screen extending alongthe magnetic disk in a region on an lower side of the loading/unloadingmechanism with respect to the direction of rotation of the magneticdisk.
 11. The magnetic disk device according to claim 5, wherein one endof the air passage is located on a line passing the center of themagnetic disk and at an angle in the range of 10° to 30° about thecenter of the magnetic disk measured in the rotating direction of themagnetic disk from a line passing the loading/unloading mechanism andthe center of the magnetic disk.
 12. A magnetic disk device comprising:a magnetic disk for recording information; a spindle motor for drivingthe magnetic disk for rotation; a magnetic head for writing informationto and reading information from the magnetic disk; a carriage armsupporting the magnetic head; a voice coil motor for moving the carriagearm; a loading/unloading mechanism for retracting the carriage arm froma position on the magnetic disk; a shroud forming a peripheral wall; anair passage passing between the voice coil motor and the shroud, andconnecting an upper side of the carriage arm with respect to thedirection of rotation of the magnetic disk to a lower side of theloading/unloading mechanism with respect to the direction of rotation ofthe magnetic disk; and a filter placed away from an outer edge of themagnetic disk and wholly within the air passage to clean air inside thedisk drive.
 13. The magnetic disk drive according to claim 12, whereinsaid filter is placed inside the air passage formed by the voice coilmotor and the shroud.
 14. The magnetic disk drive according to claim 12,wherein said filter is placed in a lower side of the air passage. 15.The magnetic disk drive according to claim 12, wherein a direction ofrotation of the magnetic disk is the same as the direction from aportion of the carriage arm supporting the magnetic head toward a baseend of the carriage arm.
 16. The magnetic disk drive according to claim12 further comprising a screen extending along the magnetic disk in aregion on an upper side of the loading/unloading mechanism with respectto the direction of rotation of the magnetic disk.
 17. The magnetic diskdrive according to claim 12, further comprising a screen extending alongthe magnetic disk in a region on an lower side of the loading/unloadingmechanism with respect to the direction of rotation of the magneticdisk.
 18. The magnetic disk device according to claim 12, wherein oneend of the air passage is located on a line passing the center of themagnetic disk and at an angle in the range of 10° to 30° about thecenter of the magnetic disk measured in the rotating direction of themagnetic disk from a line passing the loading/unloading mechanism andthe center of the magnetic disk.